Process and apparatus for bending glass sheets



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PRCBSS'D APPARATUS FOB BENDING GLASS SHEETS Filed March 30, 1938 8Sheets-Sheet 5 April 22, 1941. L v. BLACK Erm. 2,239,546'

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PRGCSS AND APPARATUS FOR BENDING GLASS SHEETS Filed March 30, 1938 8Sheets-Sheet 8.

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Patented pr. 22, 1941 UNITED STATES PATENT oFFIcE PROCESS AND APPARATUSFOR BENDING GLASS SHEETS Lloyd V. Black and Gerald Z. Minton, Tarentum,

Pa., assignors to Pittsburgh Plate Glass Company, a corporation ofPennsylvania Application March 30, 1938, Serial No. 198,870

14 Claims.

The invention relates to a process and apparatus for bending glasssheets, and has for the principal objects the provision of "an improvedprocess and apparatus, which will bend the sheets without marring themand without danger of breakage. A further object is the provision ofapparatus of cheap simple character which is easily handled and readilysubject to adjustment foriproducing a wide range of bends in sheets ofall sizes within the capacityof the apparatus.

A still further object is the provision of apparatus in which the areaof contact of the bending members with the sheet is very small, so. thatsuch members offer little interference with the uniform cooling of thesheet in the subsequent treatment thereof, such as in annealing thesheet or in subjecting it to other cooling treatment; thus permittingthe desired reduction in temperature more quickly and with lessliability of fracture than would otherwise be the case.

In carrying out the process, the sheet to be bent is' supported invertical position, in such manner that it is free to move to the desiredcurvature under the action of the bending devices, which are preferably,although not necessarily, wires so positioned and tensioned -that theyapply yielding pressure tending to bend the sheet to the desiredcurvature. When the sheet is heated to the softening point, the pressureof the wires becomes automatically effective to bend the sheet to thedesired contour. The wires are preferably applied in pairs, with onemember of each pair on one side of the sheet and the other member ofeach pair on theV other side, but if desired, the wires may all be onone side of the sheet with a Xed templet on the other side, the wiresserving to bend the sheet against the templet which thus positivelygoverns the amount of bending movement. In the first form of apparatus,the sheet is preferably hung from its upper edge and the bending wiresare arranged vertically, while in the second form, the sheet issupported on its lower edge and the wires are preferably arrangedhorizontally.

l The processis illustrated as. applied tothe bending of single sheetsof glass, but in case the sheets are to be used in making safetyglass,which requires two sheets of a curvature such that they will i-lt eachother when nested together l the apparatus are shown in the accompanyingdrawings, Wherein: A

Figure 1 is a side elevation of the complete apparatus in connectionwith the heating means. Fig. 2 is a side elevation o f the portion ofthe apparatus to which the invention particularly relates. line III-IIIof Fig. 2. Figs. 4 and 5 are vertical sections on the lines IV-IV andV--V respectively of Fig. 2. Fig. d is a side elevation of a modifiedconstruction. Fig. 7 is a vertical section through -the structure ofFig. 6. Figs. 8 and 9 are enlarged detail view s of parts of the Fig. 6construction, Fig. 8 being a plan view and Fig. 9 a side elevation. Fig.10 is a sectional view showing a modified means of supporting the glasssheet in the Fig. 6 construction. Fig.` 11 is a side elevation of`another modification. Fig. 12 is an edge elevation of the Fig. 11construction. Fig.

13 is a horizontal section on the line XIII-XIII of Fig. 11. Fig. 14 isa side elevation illustrating a modification in detail of the Fig. 11construction. Fig. 15 is a side elevation of a detail of the Fig. 14construction. Fig. 16 is a diagrammatic front elevation of anothermodification. Fig. 17 is a horizontal section on the line XVII- XVII ofFig. 16. Figs. 18 and 19 show still another 'modiiicatiom Fig. 18 being`a side elevation and Fig. 19 an edge elevation. Fig. 20 isa frontelevation of a modification of the structure of Figs. 18 and 19. AndFig. 21 is a diagrammatic side elevation showing another modification.

Referring to the drawingsthe general arrangement as shown in Fig. 1involves the use of an overhead rail 23 and the carrier 24 provided withthe Wheels 25,riding upon the flanges of the rail 23 and adapted tocarry the glass sheet into the furnace in which it is heated to thesoftening temperature preliminary to bending. The furnace comprises acasing 26 adapted to surround the carrier and provided with suitableheating means for bringing the glass to the softening temperature as itprogresses through the furnace, this being a type of furnace well knownin the art. The heating may be accomplished in any suitable manner themeans shown being electrical resistance elements 21 arranged in parallelin the side walls of the casing and having a suitable current supply.The glass sheet is heated to the softening point in this portion 'of theapparatus and is then carried forward through the furnace to anneal itor to cool it, depending on the character of the product which it isdesired to produce. If the rsheet is to be annealed, the temperature ofthe furnace Fig. 3 Kis a horizontal section .on thetached to the bar 45.

gradually decreases through the critical annealing range and `inallyreaches a point at the outlet end, Where the glass has a temperature topermit it to be safely removed from the furnace when annealed.

The portion of the apparatus to which the invention particularly relatesis shown in Figs. 2 to 5, wherein 28 is the supporting bar which carriesthe wheels 25 land from Whicha frame is hung comprising the side bars28, 29, the curved top bar 30 *and the similarly curved bottom bar 3|.'I'he glass sheet 32 is supported in theV frame from two collars 33clamped in position by means of the set screws 34, such collars carryingthe tongs 35 whose upper ends are connected tothe collar by the links 36so that the weight of thev sheet insures a proper gripping action oi thepoints of the tong upon the glass. These tong supports are applied atpositions along the upper edge such that in the bending operation, thesepoints of support doV not depart during the bending operation from thevertical plane in which they are originally applied.

The bending of the glass sheet when it reaches the softening point atwhich ,it will bend without niarring, is accomplished by means of twosets of wires 31, 38, the wires 31 lying on one side of y, the sheet,and the wires 38 on the other side.

These wires extend at their upper endsthrough two sets of perforationsin the barv 30 which sets are spaced apart approximately A the thicknessof the glass sheet 32./ At their lower ends these wires extend throughsimilar holes in the bot- .tom bar 3| and are provided with the weights39 and "40. As indicated in Fig. 3, the bars 30 and 3| are curved tocorrespond `with the curvature which it is desired -to produce in theglass sheet 32, so that when the plate is positioned between the twosets of wires, they tend to bend it to the contour of the bars 30 and3|. Any bending of the plate is, of course, resisted by the stiiness ofthe plate when it is cold, but when it is heated to the softening point,it is bent so that it corresponds to the curvature of the bars 38 and3l. A part of the wires, 'such as 38 (Fig. 5) tend to bend the plate,while another part thereof merely acts to limit or determine the bendingmovement of the glass. Some of the'wires on each side of the plate,however, apply bending pressure to the sheet and the two sets togethergive the desired curvature when the glass is softened to the properdegree. In practice, this procedure operates to give the necessarybending eiect withou?l marring the glass since the bending temperatureis below the marring temperature. After the glass has been bent, itvsets in this bending position as the carrier moves along the heatingkiln to a position of lower temperature. It will be noted that theamount of force required to bend the sheet is relatively slight, sincethe sheet is so'supported that it is perfectly free to move in arrivingat the curvature as dictated by the position oi the wires.

While the wires are\preferab1y tensioned by means of weights, it ispossible to accomplish the same tensioning function by the use of Isprings and this construction `is illustrated in Figs. 6 to 10, whereinthe pairs of wires 4| and 42 are fixed at their lower ends with respectto the bottom bar 43 and are tensioned at their upper ends by means ofthe springs 44 which are at- In this construction the side bars of the/frame" comprise thev pairs of parallel members 46 connected at theirupper and lower ends by the looped portions 41 and 48. 75

The positions of the pair of wires is in this case determined by theposition of the brackets 48- and carried by the cross bars 5| and 43.The brackets 49 and 50 are mounted on screws 52 and 53, which extendtransversely of the bars 5I and 43 and are welded thereto at their ends.'Ihe position of the brackets longitudinally of the screws is determinedby the nuts 54 mounted on the screws on either side of the brackets. The

brackets 48 are provided at their lower edges with flanges 55 (Figs. 8and 9) and the pairs of wires 4| and 42 extend through the perforations56 in these anges. Similarly, the brackets 50 are provided at theirupper ends with iianges 51 having pairs of perforations through whichthe lower ends of the wires extend and are secured. The brackets 49 and58 may be adjusted on the screws 52 and 53 so that the pairs of wireslie in diierent planes and thus tend to bend the glass sheet 58 to thedesired curvature when it is heated to the softening point. 'I'headvantage involved in the use of the brackets, as compared with theconstruction of Figs. 1 to 5, is that the use of the brackets permitsthe wires to be adiusted'in a wide variety of ways` so that diierentcurvatures may be produced on the apparatus depending upon therequirements. As indicated in Fig. 7, the springs 44 lie outside theupper wall of the furnace, the slot being made tight by the flexibleasbestos seals 58a.

In order to support the glass sheet 5,8, two of the brackets 49 may beutilized, as indicated in Figs. 6 and 9, such brackets being providedwith hooks 59 which support the blocks 60 carrying the tongs 8|, suchtongs being similar in construction to those shown in Fig. 4. In orderto facilitate the placing of the glass plate in position between thepairs of wires, a plate 62 is provided which rests at its lower edge onthe tops of the brackets 58. This plate during the bending operationlies in' a vertical plane, as indicated in Fig. 7, but when it isdesired to separate the wires to facilitate the insertion of the glasssheet, the plate is turned so that it lies in a horizontal plane, asindicated in the dotted lines in Fig. 7,

thus spreading the wires apart as indicated by these dotted lines.

It is also possible in the construction of Fig. 6 to support the glassplate 58 from the bars 5I o by the provision of means, as indicated inFig. 10,

such means comprising hook members 53 which support the tongs 84. It theglass sheet is supported by this method, it becomes necessary tovposition the tongs inthe same manner as de-` In the construction ofFigs. 11 to 13, templets are employed for governing the bending movementof the glass plate 65 and the bending operation is accomplished by meansof the single set of wires 68 which are arranged horizontally,

' instead of vertically as in the constructions heretofore described. Inthis apparatus, the glass' .plate instead of being hung from its upperedge 1s supported at its lower edge upon the rollers 61 mounted on thebottom bar 68 of the frame,

which support permits the sheet to move freely in its bending movement.Two vertical templet bars 69 are employed, such bars being secured tothe frame at their upper and lower'ends by the brackets 18 and 1| (Fig.12)'. The curvature or the plate is determined by the curve of thevpivoted together at |03 and carrying the weights A front side of Vthesetemplat'plates, Vas indicated by the dotted lines 12 (Fig. 12). Thewires 88 are attached at their right hand ends (Figs. 11 and 13) to thebrackets 13 carried by the side frame member 14, such brackets all beingprovided with slots to permit of their adjustment, and are clamped bythe bolts 14a.' The other ends of the wires are attached to quadrantmem.. bers 15 pivoted on the brackets 16 (Fig. 12), such brackets beingslotted and secured to the side member 11 of the frame by means of thebolts 18, so that the position of the quadrant members may be adjustedfor dierent curvatures to correspond to the adjustment of the brackets13.

Y The quadrants are provided with counterweighted arms 19 which tend toswing them in a counterclockwise direction and thus tension the wires66. When the glass plate-reachesa bending temperai ture, the pressure ofthe wires thereon bends it to the curved shape indicated in dotted linesin Fig. 12, at which time,the movement of the plate is stopped by thetemplet plates 69, which thus positively determine or fix the curvatureof the plate.

Fig. 14 illustrates a departure from the means of tensioningthe wires 66of the Fig. 11 construction in that each end of each wire 66 is providedv with a weight 80 and passes over pulleys 8|. These pulleys are mountedon slotted arms 82 (Fig. 15) so that the position of the wires may beadjusted to suit varying, curvatures, as heretofore pointed out. Thepulleys 8| are preferably mounted on swivel joints 83 so that thepulleys can adjust themselves to the angle of the wiresSS. 1

Figs. 16 and 17 illustrate diagrammatically a modification inwhichtemplets are employed for adjusting the position of the sets ofwires 8l and 85 for bending theglass sheet 86. These wires are carriedin a frame made up of the top and bottom bars 81 and 88, the side bars89 and inter.. mediate bar 90. 'I'he wires carry at theirV lower endsthe tensioning weights 9| and may be adjusted to suit varying curvaturesby means of the pairs of templets 82 and 93 which have their opposingedges of theV desired contour, as indicated in Fig. 17. These templetsare clamped in position by means of bolts 94 extending through slots inthe templets to permitoi adjustment. The bars 88 and 90 aremade/in pairsspaced apart to avoid contact with the wires.

" When it is desired to bend a sheet to a different curvature, all thatis necessary is to substitute \`\new templets 92 and 93 having theiredges of the right curvature. No means are shown in this constructionfor supporting the glass sheet 86, but it `will be understood that thesheet may be supportetlas heretofore described in connection with otherforms of the device; also that springs may be used for tensioning thewires instead of the weights.

Figs. 18 and 19 illustrate diagrammatically ani end of each wirecarrying a weight II2.

other form of construction in which a pair of metallic grids 95 and-.areemployed for bending the sheet 91 to the desired curvature, the glasssheet in this case beinghung from its upper edge by means similar tothat heretofore described. The grids are formed ofthin metal verticalstrips 98 and transverse Vstrips 98 suitably secured together at theirintersections and supported fromvthe bar |00 by means of the flexiblemembers IOI. The lower edges of the grids are moved -yieldingly towa'rdseach other by any suitable means, such as the crossed levers |02 Fig.v20 illustrates another modification, in whichthe grid structure ofFigs. 18 and 19 is replaced by the vertical bars |05 lying on each sideof the glass sheet and supported in the same manner as the gridsheretofore described.l The lower ends oi these bars may be pressedtoward each other by the same means as that shown `in Fig. 19, or mayeach merely carry a weight Ilia. It will be understood that the verticalbars |88 are of relatively thin sheet metal and should have either acurvature similar to that of the grids and 86, or should be hung oncurved members at their upper ends so that they function like the wiresof the Figs. 2 to 5 construction. In some cases the weight of the barsof Fig. 20 and the grids of Figs- 19 and 20 may be sufficient to givethe necessary bending effect without the use of the weights at the lowerends thereof.

Fig. 21 illustrates diagrammatically still another bending arrangement,in which a fixed grid I 08 lying on one side of the glass sheet |01 actsas a templet and the bending vis accomplished by means oi' -thesingleset of wires |00 secured at their upper ends to a bar |009 and passingaround the guide pulleys IIO and III, the lower In this case, the glasssheet is supported from beneath on bars Ill as in the construction ofFig. 11, instead of being suspended from its upper edge, anti-frictionrolls being preferably employed upon such bar as heretofore described'.This structure is. the equivalent of that of Fig. 11 except that thewires are arranged vertically instead of horizontally. It will beunderstood that in all the various forms of construction, the springsfor tensioning the wires may be substituted for the weights along theline of the disclosure of Fig. 6, the use' of weights, however,

refers to the point in temperature at which the4 glass loses itsrigidity so thatit maybe bent;v

rather than to the point at which the surface becomes sensibly soft sothat it will take an impression from the bending members. Thetemperature required varies somewhat with the glass composition; rangingaround 1050 deg. F., and must be regulated within somewhat narrowlimits.

What we claim is:

1. A method of bending a glass sheet which comprises supporting it in a.vertical position in such relation as to be freely responsive to forcestending to bend it, applying over the area of the sheet on oppositesides thereof a plurality of light metallic members in spaced parallelrelaltion, supporting the metallic members under tension in such mannerthat they tend to assume positions deiining a curved zone and to exertin such manner that they tend to assume positions defining a curved zoneand to exert pressure on the sheet preliminary to the heating thereofand then heating the .sheet to softening temperature sothat said membersbend it to the shape of said zone, while at the same time opposing onthe sheet theA forces exerted by the members tovinsure bendin actionthereof.

3. A method of bending a glass sheet which comprises supporting it in avertical position in such relation as to be freely responsive to forcestending to bend it, applying over the area of the sheet on one sidethereof a plurality of light metallic members in spaced parallelrelation, supporting the metallic members under tension in such mannerthat they tend to assume positions defining a curved zone and to exertpressure on the sheet preliminaryto the heating thereof and then heatingthe sheet to softening temperature so that said members bend it to theshape of said zone, while at the same time opposing on the sheet the.forces exerted by the members to insure bending action thereof, andpositively resisting bending movement of the glass sheet on the si'dethereof opposite the application of said members when the sheet has beenformed to the shape of the curved zone.

4. A method of bending a glass sheet which comprises supporting it alongits lower edges and in a vertical position'in such relation as to befreely responsive'to the forces tending to bend it, applying over thearea of the sheet on one'side thereof a plurality of light metallicmembers in spaced parallel relation supporting the metallic membersunder tension in such manner that they tend to assume positions defininga. curved zone and to exert pressure on the sheet preliminary to theheating thereof, and then heating the sheet to softening temperature sothat said members bend it to the shape of said zone, while at the sametime opposing on the sheet the forces exerted by the members to insurebending action thereof. l

5. A method of bending a' glass sheet Awhich comprisesY suspending italong its upper edges in a vertical position in such relation as to befreelsr responsive to the forces tending to bend it, applying over thearea. of the sheet on one side thereof a plurality of light metallicmembers in spaced para/llel relation, supporting the metallic membersunder tension in such manner that they tend to assume positions defininga curved zone and to exert pressure on the sheet preliminary to theheating thereof and then heating the sheet to softening temperature sothat said members bend itfto the shape of said zone, while at the sametime opposing on the glass sheet the forces exerted by the members toinsure bending action thereof.

6. A method `of bending a glass sheet which comprises supporting it in averticalpositlon in such relation as to be freely responsive to forcestending to bend it. applying over the area of one side of the glasssheet a series of lightmetallic members normally positioned along a zoneof predetermined curvature and adapted to be held out of said zone bythe unbent glass sheet in its vertically supported position before saidglass sheet responds to bending action, applying opposed70 tensionalforces to opposite extremities of the light metallic members tending tomaintain them along the predetermined zone, holding the glass sheet inopposition to the bending forces of the light metallic members toprevent its displace- 2,239,546 supporting the metallic members undertension ment, and heating the glass sheet to softening temperature untilit bends to the shape of said zone under the influence of the forcesexerted by the light metallic members. i

\ 7. An apparatus for bending a 'glass sheet comprising means forsupporting the sheet in vertical position in such relation as to befreely re'- sponsive to forces tending to bend it, two spaced series oflight metallic members arranged to denne between them a curved zone,means vsupporting the metallic members in such manner that the twoseries of said members may be displaced for insertion of said glasssheet between them, and means placing said metallic members undertension so that they tend, when displaced, to return to their originalpositions and thus reestablish said curved zone.

8. An apparatus for bending a glass sheet comprising means forisupportnga sheet in vertical position in such relation as to be freely responsiveto forces tending to Vbend it, a series of light metallic membersarranged to denne therealong a predetermined curved zone, backing meansassociated with said members and cooperating therewith along theboundaries of said curved zone to hold the glass sheet, meansdisplaceably supporting the metallic members whereby the latter aremovable to receive the glass sheet between the series of them and saidbacking means, tensioning means connected to the members and exertingforces tending to maintain members in their zone-defining relation andoperative to return -them'to their original zone-defining position afterthey have been displaced therefrom.

9. An apparatus for bending a glass sheet comprising means forsupporting a sheet in vertical position in such relation as to be freelyresponsive to forces tending to bend it, a series of light metallicmembers arranged to define therealong a predetermined curved zone, atemplet located in opposed relation to said members and cooperatingtherewith along the boundaries of said curved zone to hold the glasssheet, means displaceably supporting the metallic members whereby thelatter are movable to receive the glass sheet between the series of themand said templet, 'tensioning means connected to the members andexerting forces tending to maintain the metallic members in theirzone-defining relation and operative to return them to their originalzone-defining position after they have been displaced therefrom. y

10. An apparatus for bending a glass sheet comprising means forsupporting the sheet in a vertical position in such;lrelation as to befreely responsive to forces tending to bend it, a series of wiresarranged tofdene therealong a predetermined curved zone, backing meansassociated with said wires/and cooperating therewith in establishingboundaries of the curved zone. means displaceably supporting the wiresin such m'anner as to be laterally movable for insertion of lsaid glasssheet between the series of them and porting the wires in such manner asto be lateral. ly movable for insertion of said glass sheet between thetwo series of them, and tensioning means connected to thewires andexerting forcestending to maintain the Wires in their zoneformingrelation and operative to return them to their original zone-formingposition after they have been displaced therefrom.

12. An apparatus for bending a glass fsheet comprising the means forsupporting the sheet in a vertical position in such relation as to befreely responsive to forces tending to bend it, a series :of lightmetallic members arranged to define means connected to said members andexerting forces tending to maintain the members in their curvedzone-forming relation and operative to return them to their originalzone-forming relation after they have beendisplaced therefrom.

13. An apparatus for bending a glass sheet comprising means forsupporting the sheet in a vertical position in such relation as to befreely responsive to forces tending to bend it, a series of wiresarranged to define therealong a predetermined curved zone, backing meansassociated with said wires and cooperating therewith along the`boundaries of the curved zone to hold the glass sheet, meansdisplaoeably supporting the wires whereby the latter are laterallymovable for insertion of said glass sheet between the series of them andsaid backing means. tensioning means connected to the wires and exertingforces tending to maintain the wires in their zone-forming relation andoperative to return them to their original zone-forming position afterthey have been displaced therefrom, and means for heating the sheet tosoftening temperature while the sheet is associated with the wireswhereby lthe wires respond to the tensioning means in bending the glasssheet.

14. An apparatus for bending a glass sheet comprising means forsupporting the sheet in a vertical'position in such relation as to befreely responsive to forces tending to bend it, a series of wiresarranged to dene therealong a predetermined curved zone, backing meansassociated with said wires and cooperating therewith along theboundaries of the curved zone to hold the glass sheet supporting thewires displaceably whereby the latter are laterally movable forinsertion of said glass sheet between the series of them and saidbacking means, tensioning means connected to the WiresV and exertingforces tending to maintain the wires in their zone-forming relation andoperative to return them to their original zone-forming position afterthey have been displaced therefrom, heating means,. and means forcarrying the glass sheet supported by said series of wires and backingmeans into the heating means.

LLOYD V. BLACK. GERALD Z. MINTON.

